In semiconductor wafer processing, temporary bonding and debonding techniques are necessary for thin wafer backside processes. The wafer is bonded on rigid carrier by adhesive layers. After grinding and/or other post-bonding processes the wafer is debonded from the rigid carrier.
One of the conventional debonding methods uses a laser on a light-to-heat conversion layer (LTHC) to release the carrier, and then peel off the adhesive. The adhesive material is UV-cured material, e.g. thermal setting polymer that cannot be stripped by chemicals and should be peeled off instead. This method suffers chemical residue after debonding. Also, the laser release layer has a weak chemical resistance during backside processes.
Another conventional method uses chemical release. This method chemically dissolves the adhesive to release the wafer from the carrier. This method needs perforated glass and easily induces cross contamination. The process speed, e.g. wafers per hour (WPH) is also slow compared to the other methods.
Yet another conventional method is thermal sliding. This method treats the wafer and carrier with heat and then slides them apart. This method needs higher debonding temperatures and may adversely impact the interconnection scheme.
Accordingly, new structure and methods are desired for a robust wafer bonding to ensure surface cleanness after debonding and to have good chemical resistance during post-bonding processes.